US7478650B2 - Inversion liner and liner components for conduits - Google Patents

Abstract

Inversion liners are provided which in a first embodiment include first and second flexible fabric layers joined to first and second high strength fiber containing layers and joined in tubular form. The first and second flexible fabric layers face one another. The second glass fiber containing layer further is bonded to a thin, third flexible fabric layer. A substantially fluid impermeable layer is applied to the opposite side of the thin, third flexible fabric layer.

Description

This application is a continuation-in-part of U.S. patent application Ser. No. 10/422,451, filed Apr. 24, 2003 now U.S. Pat. No. 6,837,273, which is a continuation-in-part application of U.S. patent application Ser. No. 10/174,580, filed Jun. 19, 2002 now U.S. Pat. No. 7,096,890 , entitled “Inversion Liner and Liner Components for Conduits” filed Jun. 19, 2002, and is related to commonly assigned U.S. Pat. Nos. 5,836,357; 5,931,199; 5,911,246 and 5,873,391, which are all hereby incorporated by reference herein in their entireties.

FIELD OF THE INVENTION

This invention relates to conduit liners for making repairs in underground piping systems, and more particularly, to inversion liners that provide improved strength and greater inversion speed.

BACKGROUND OF THE INVENTION

Underground piping systems are essential in providing the transportation of liquids and gases to homes and businesses. Used mostly by utilities in sewer pipes, water pipes, water mains, gas mains, electrical conduits and other applications, such pipes are often found many feet under ground or in inaccessible areas, such as under buildings or roadways.

Due to cyclical loadings, premature wear, manufacturing defects, corrosion, and other factors, these pipes can often develop cracks or weakened areas requiring repair. Since the replacement of underground pipes is extremely costly, an alternative is to provide a lining repair while leaving the remaining pipe structure in place. Various types of lining products have been commercialized in the past, some flexible, some rigid and some flexible when applied, but rendered rigid by a resin after application. In most cases, it is highly desirable to closely conform the lining to the inner surface of the pipe. This has been generally accomplished by pressure-expandable techniques and inversion techniques.

In a “pressure-expandable” technique (also called the “winch-in-place” technique), a pliable polyester felt sleeve, which has been previously impregnated with a thermosetting resin is inserted into a damaged pipe portion and pressurized so that the resin-impregnated liner presses firmly against the inner wall of the damaged pipe. The expanded liner is then permitted to cure to form a new lining within the original pipe. More recently, pressure-expandable conduit liners have been introduced with glass reinforcement dispersed along the inner and outer surfaces of the liner. See Kittson, et al., U.S. Pat. No. 5,836,357, which is hereby incorporated by reference.

In the “inversion” technique, the pipe liner is first impregnated with a suitable curable synthetic resin. The resin-filled liner is next inserted into a pipe. The leading end of the liner is turned back onto itself and fixed to the lower end of a feed elbow of a manhole. A fluid, such as water or air, is pumped into the feed elbow which causes the liner to invert into and along the interior of the pipe. The liner is maintained in engagement with the pipe until the resin cures. After the resin cure has been completed, the fluid is drained from the inside of the liner, thus leaving a hard, rigid lining applied to the pipe's inner surface.

Most inversion liners are formed of heavily needled felt of polyester or acrylic fibers. Needling causes the fibers to generally extend in right angles to the plane of the material.

Efforts to improve upon the mechanical properties of felt liners have included flowing chopped glass fibers onto the felt web prior to needling, Wood, U.S. Pat. No. 4,390,574, or needling the felt with reinforcing fibers, such as carbon fibers, Kevlar® fibers or high tenacity polypropylene fibers, such as disclosed in Wood, U.S. Pat. No. 4,836,715. Other techniques include the use of glass fiber cloth, mat or felt, or a non-woven felt of a mixture of synthetic and glass fibers, such as disclosed in Kamiyamma, et al., U.S. Pat. No. 6,018,914.

The introduction of glass or other high strength fibers in needling operations, while increasing the average tensile strength of the fibers themselves, still presents a less than desirable orientation, since the needled reinforcing fibers are also generally disposed at right angles to the plane of the material.

Kittson, et al., U.S. Pat. No. 5,836,357, shown inFIG. 2, teaches the use of glass roving in conjunction with chopped glass fibers for improving the tensile strength in at least the longitudinal direction of the liner. The Kittson et al. liner is “glass-faced”, being formed by a pair ofglass fiber layers2 and3 stitched with a thread to a pair of feltlayers4 and5, and sewn together in a tubular form. While this dramatically improves the liner's mechanical properties, this liner has not been recommended for inversion techniques, and was designed for winch-in-place applications. The Kittson, et al. liner is also difficult to “build”, as in the subsequent building-up of additional liner layers or “blocks” due to the fact that glass layers are not “heat bondable” through conventional means. In addition, a separate impermeable foil or film must be added to contain pressure for expansion of this liner by heated fluids. Moreover, artisans have generally regarded building up layers of liners within an underground pipe to be impractical.

Accordingly, there remains a need for an inversion liner that can optionally be built up, such as by heat bonding or by adhesive bonding, for example, with several liner layers for large diameter pipe and manhole applications. There further remains a need for a reinforced inversion liner material, suitable for small and large conduits alike, which can be made thicker by layering a number of simple building blocks, preferably without significantly affecting the overall modulus of the liner.

SUMMARY OF THE INVENTION

In some embodiments, a method of making a tubular inversion liner or liner block comprises providing a first flexible fabric layer fastened to a first high strength fiber containing layer; providing a second flexible fabric layer fastened to a second high strength fiber containing layer; combining the first and second flexible fabric layers and the first and second high strength fiber containing layers by melt bonding or adhesion without stitching or needling, so that the first and second flexible fabric layers face one another, and are sandwiched between the first and second high strength fiber containing layers; and providing a substantially fluid impermeable layer on the second high strength fiber containing layer, the substantially fluid impermeable layer becoming the outermost layer prior to inversion.

In some embodiments, a pressure-expandable tubular liner for conduits, including at least one liner block, comprises a first flexible fabric layer fastened to a first high strength fiber containing layer. A second flexible fabric layer is fastened to a second high strength fiber containing layer. The first and second flexible fabric layers and the first and second high strength fiber containing layers fastened are together by melt bonding or adhesion without stitching or needling whereby the first and second flexible fabric layers face one another and are sandwiched between the first and second fiber containing layers. A a substantially fluid impermeable layer is joined to at least one of the high strength fiber containing layers.

In some embodiments, a pressure-expandable tubular liner for conduits, comprises a first flexible fabric layer fastened to a first high strength fiber containing layer and a second flexible fabric layer fastened to a second high strength fiber containing layer. One or more additional flexible fabric layers, are each joined to one of the group consisting of the first flexible fabric layer, the second flexible fabric layer, and another of the one or more additional flexible fabric layers by melt bonding or adhesion without stitching or needling whereby the one or more additional flexible fabric layers are sandwiched between the first and second fiber containing layers. A substantially fluid impermeable layer is joined to at least one of the first and second high strength fiber containing layers.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings illustrate preferred embodiments of the invention according to the practical application of the principles thereof and in which:

FIG. 1: is a diagrammatic cross-sectional view illustrating a preferred double-block inversion liner of this invention disposed within a pipe;

FIG. 2: is an enlarged cross-sectional view of a segment of a typical prior art lining having a glass-faced construction;

FIG. 3: is an enlarged cross-sectional view of a segment of a preferred liner of this invention;

FIG. 4: is an enlarged cross-sectional view of a segment of a composite double-block liner, including the liner ofFIG. 3;

FIG. 5: is an enlarged cross-sectional view of a segment of an improved glass-faced liner of this invention;

FIG. 6: is an enlarged cross-sectional view of a segment of a composite triple-block liner, including the double-block liner ofFIG. 4; and

FIG. 7A: is an enlarged cross sectional view of a segment of a liner or liner block having a thin veil coated with a liquid impermeable layer.

FIG. 7B is a view of a segment of a liner or liner block in which the impermeable layer is directly joined to one of the high strength fiber containing layers.

FIG. 8 is a cross-sectional view of another embodiment of a liner in which adjacent flexible fabric layers are heat or adhesive bonded to each other.

FIG. 9 is a cross sectional view of another embodiment of a liner having additional adjacent flexible fabric layers heat or adhesive bonded to each other.

FIG. 10 is a cross sectional view of another embodiment of a liner having alternating glass and felt layers at the interior and exterior of the liner, with additional adjacent flexible fabric layers therebetween.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

In a first embodiment, the present invention provides a method for making a tubular inversion liner, or liner block. This method includes the steps of providing first and second flexible fabric layers fastened to first and second high strength reinforcing fiber containing layers (e.g., glass-containing layers), respectively, followed by combining the first and second flexible fabric layers and the first and second high strength reinforcing fiber containing layers so that the first and second flexible fabric layers are sandwiched between the first and second high strength reinforcing fiber containing layers. The method further includes the step of joining a third flexible fabric layer, which is much thinner than the first and second flexible fabric layers, to the first or second high strength reinforcing fiber containing layer. Finally, a substantially fluid impermeable layer is applied to the third flexible fabric layer such that the impermeable layer becomes the outermost layer of the liner, or liner block prior to inversion.

One embodiment of the present invention provides a more efficient construction method than those previously provided in the inversion liner field. By stitching, gluing or heat bonding a thin veil, having a thickness of about 0.1 to about 1.0 mm, to the second high strength containing layer, and applying an integral fluid impermeable layer on the veil, a tubular inversion liner can be manufactured with a reduced number of layers, which makes the inversion liner easier to invert, lighter to carry and cheaper to manufacture.

In a further embodiment of this invention, a method of manufacturing a tubular inversion liner, or liner block, is provided which includes the steps of providing first and second flexible nonwoven polyester fabric layers, each of which is fastened to a high strength fiber containing layer. The method further includes stitching, or otherwise attaching, a nonwoven spun-bonded polyester veil, together with the first and second flexible nonwoven polyester fabric layers and the first and second high strength fiber containing layers, whereby the veil is attached to the second high strength fiber containing layer, followed by joining a substantially fluid impermeable layer to the nonwoven polyester veil. The substantially fluid impermeable layer then becomes the outermost layer of the liner, or liner block, prior to inversion, and becomes the innermost layer after inversion.

An embodiment of the present invention is related to inversion liners of the type that can be inverted with the assistance of fluid pressure, such as compressed air, steam or hot water (hereinafter “fluids”) to expand within a defective conduit and generally, mechanically mate or bond within, or come in close proximity to, the inner diameter of the conduit prior to curing to form a substantially corrosion and water resistant sleeve. As such, the liners of this invention are thin, tubular members which can exhibit a tubular, tape-like or ribbon-like cross-section prior to inversion. As used herein, the term “buildable” refers to the ability of the liners of this invention to be adhesively bonded to a second or subsequent liner block to build up the thickness of the liner to its final thickness, and the term “glass-faced” means a liner having at least one glass layer located on, or proximate to, its face or faces. Building techniques for liner materials are often useful for large pipes of 36-40 inches or greater in diameter, in which liner building blocks of about 4 to about 14 mm are added together to build up to a thickness of about 12 to about 50 mm in final thickness, for example. This building can be done whenever the tube is assembled, by the manufacturer or installer, for example, preferably before inversion or installation. Alternatively, the liners according to some embodiments of this invention can be made with thicker layers or more layers of fabric disposed between two high strength fiber-containing layers (e.g., glass fiber containing layers), which in turn can be made thicker, to achieve final product thickness. The liners described herein provide high flexural modulus and strength but are still vibration and corrosion resistant.

With reference to the drawings, and particularlyFIGS. 1 and 3 through7B thereof, there is shownpreferred inversion liners300,500, and600 or liner blocks100,200,400 and850. For example,liner block100, shown inFIG. 3, contains first and second flexible fabric layers18 and28 which are adhesively, mechanically and/or heat bonded to one or more high strength fiber containing layers (e.g., glass fiber containing layers)24 and34. This is accomplished, for example, bystitch thread33 sewn to bond thefabric layer18 to the glassfiber containing layer24, and theflexible fabric layer28 to the glass fiber-containinglayer34, followed by stitching all of theselayers28,38,24 and18 together. The resultingliner block100 includes one or more longitudinal seam portions, preferably an outer seam portion and an inner seam portion which are preferably not radially aligned so as to avoid a continuous radial discontinuity through the wall thickness ofliner block100, as described in Kittson et al., U.S. Pat. No. 5,836,357.

In the embodiment ofFIG. 3, glass-faced needled felt is manufactured in blankets by disposing chopped glass and/or glass roving onto a moving felt. The glass fibers are stitched or sewn onto each of the flexible fabric layers18 and28 separately, thus forming, in the preferred embodiment, individual glass containing layers, such asglass containing layers124,134,234,224,334,324,824,834,24 and34. These “layers” can be continuous or discontinuous, meaning that there may be gaps or undulations in the glass containing layersglass containing layers124,134,234,224,334,324,824,834,24 and34. Theglass containing layers24,34,124,134,234,224,324,334,824 and834 may or may not be needled, stitched, flame bonded and/or adhesive bonded to themselves or to other components of the liner blocks100,200,400, and850, andliners300,500 and600. Glass-faced flexible fabric layers made in accordance with these teachings are cut to size and, preferably, are joined bystitches33,233 oroptional stitch833, which assembles them together as shown inFIGS. 3,5 and7A.Optional stitch833 can be used alternatively or in combination with a heat or resinous bond between the facingflexible fabric layers218 and238, or838 and818, for example, especially for total thicknesses exceeding about 7 mm. If a relatively thick liner is desired, then adjacentflexible fabric layers218 and238 or838 and818 are preferably joined to each other by heat or adhesive bonding without stitching or needling, so that the total liner thickness is not limited by the capabilities of stitching or needling equipment. This is described below with reference toFIGS. 7B-10. Alternatively,glass containing layers24,34,124,134,234,324,334,824 and834 can comprise preformed glass mats stitched or needled into the flexible fabric layer, for example. Additionally, instead of two glass containing layers, such asglass containing layers24 and34, a single layer, such as a double thickness glass layer, can be applied to one of the flexible fabric layers, such asflexible fabric layer28, without adding glass fibers to the other, such asflexible fabric layer18.

Liner orliner block100 is illustrated to be nearly identical to liner block200, which containsglass containing layers124 and134, andflexible fabric layers148 and138. However, since liner orliner block100 is designed to be the innermost layer, following inversion, a substantially fluidresistant layer20 is applied. With other liner systems, such fluid impermeable layers were provided by a fluid impermeable foil or “calibration hose” which could be removed or left in place. Some embodiments of the present invention desirably provide thinner flexible fabric layers35 or235, such as needled polyester felt layers having a thickness of about 1 to about 3 mm. These flexible fabric layers35 and235 preferably contain a first surface, which contains flame-bondable fibers, for bonding toflexible fabric layer18 andveil228, for example. They also include a substantially fluidimpermeable layer20, such as a coating, film or saturant, having a thickness of about 0.1 to about 1 mm, so that the final thickness of the plastic-coated fabric is about 1.1 to about 3 mm, preferably about 1.2 to about 1.8 mm. Preferably, the substantially fluidimpermeable layer20 is partially disposed within the porosity of the flexible fabric layers35 and235 to form a mechanical or melt bond.

With respect to liner orliner block100, theflexible fabric35, containing the substantially fluidimpermeable layer20, is heat bonded, such as by flame tacking, to theflexible fabric layer18. In like manner, theflexible fabric layer28 ofliner100 can be flame tacked to theflexible fabric layer148 to form amelt bond126.Melt bonds26 and126, as well asmelt bonds226 and326, while strong, are temporary fastening measures, which become less important, or even irrelevant, once the resin is cured.

In the inversion liner blocks100,200,850 and400, andliners300,500 and600 according to some embodiments of this invention, the glass fiber-containinglayers24,34,134,124,234,224,334,324,834 and824 represent the reinforcement layers and are preferably of a thin cross-sectional thickness, such as less than about 10 mm, preferably about 0.1 to about 5 mm, and most preferably, about 0.6 mm, 1 mm and 1.5 mm for standard 4 mm, 6 mm and 9 mm building blocks, respectively. The flexible fabric layers18,28,138,148,238,218,318,328,35,818,838 and235 are preferably about 0.5 to about 20 mm in thickness each, preferably about 1 to about 10 mm, and most preferably about 1.33 mm, 2 mm and 3 mm for 4 mm, 6 mm, and 9 mm building blocks, respectively. Glass fiber-containinglayers24 and34 in liner orliner block100;layers24,34 and124,134 incomposite liner500;layers24,34,124,134 and324,334 incomposite liner600; and layers824 and834 inliner block850, are desirably located radially outwardly, preferably less than about 5 mm, and more preferably, less than about 2.5 mm, from the outermost fabric-containing layers, prior to inversion, so as to provide flexural modulus and strength to the cured liner or liner blocks. Accordingly, glass fiber-containing layers, such aslayers124 and134 ofcomposite liner600 ofFIG. 6, can be optionally lightened or eliminated, since they are located along a neutral axis when the laminate if flexed and do not significantly contribute to the flexural performance of theliner600.

For the glass-faced liner orliner block300, improved flexural modulus and strength is most desirably accomplished by placing theglass containing layer224 no more than about 2.5 mm from the liner's surface, and more preferably, within about 1.2 to about 1.8 mm. Thicknesses for the plastic or resin coated flexible fabric layers35 and235 should be about 0.1 to about 3.0 mm, preferably about 0.25 to about 2 mm, and more preferably about 0.75 to about 1.25 mm. Additional flexible fabric layers (not shown) can be added, adjacent tolayers218 and238, or theseflexible fabric layers218 and238 can be thicker, such as about 10 to about 20 mm, to achieve final fabric thicknesses of up to about 25 to about 44 mm, for example. In addition, the glass fiber containing layers can be about 1-5 mm, preferably about 2-3 mm for thicker liners. Theveil228 should be as thin as possible while still permitting bonding (by heat or other methods) to the next flexible fabric layer. Theveil228 should be permeable to the impregnation resin. Theveil228 may have a thickness of only about 0.01 to about 1 mm, preferably about 0.1-0.3 mm. The impermeable layer itself should be less than about 1 mm thick and, preferably, less than about 0.5 mm thick, and can be applied to theveil228, the thinflexible fabric layer235, or directly to the secondglass containing layer224, without any intermediate layers.

The preferred fabric layers18,35 and28 ofliner100; fabric layers138 and148 of thesecond liner200; fabric layers238,218,228 and235 ofliner block300; fabric layers318 and328 ofliner block400; andfabric layers818 and838 ofblock850, can be one or more sewn or bonded fabric layers, comprising a natural or synthetic fibrous material in needled, knit, woven or non-woven mat form. Suitable materials should be water and corrosion-resistant. Examples of fibers for such fabrics include pulp fiber, hemp, cotton, polyethylene, polypropylene, rayon, nylon and/or polyester fibers. In certain instances, woven or non-woven glass material can be used in addition to, or as a substitute for, these other fibers. The most preferred embodiment for the fabric layers is a needle-punched non-woven polyester or acrylic felt employing standard technology for manufacturing needle-punched materials.

The high strength fiber-containinglayers24,34,124,134,234,324,224,324,334,824 and834 of this invention preferably contain chopped glass fibers, glass roving, or both. Glass fiber compositions can include, for example, E, D, R, AR, S and/or C-type glass fibers. Such fibers can be blended with, or replaced by, thermoplastic (such as, polypropylene, polyamide, or polyethylene), or thermosetting, such as polyester, or other materials such as, carbon, graphite or basalt fiber. Although specific examples are described herein in which the high strength fibers are glass, the high strength fibers in all of the examples described herein may be replaced by any of the materials listed in this paragraph, or combinations thereof.

Alternatively, one hundred percent glass fibers can be distributed over the surface of flexible fabric layers18,28,138,148,218,238,324,334,818 and838, for example, and mechanically bonded thereto to produce a base layer for the liner blocks100,200,400, and850 andliner300. This can be accomplished using a light needling process which keeps the majority of the glass fibers properly oriented, or more preferably, a stitch mat process, in which the preferred needle punched polyester mat is stitched to a plurality (about 200-2500 g/m²) of chopped glass fibers on its top surface. The chopped glass fibers may, optionally, be added during production in several stages, which could be stitched down separately (such as in a “double glass” method). For example, up to about 1,000 g/m²of chopped glass fibers can be applied to a needle punched polyester mat. Then the fabric can be stitched and run through the stitching machine a second time with an additional 1,000 g/m²of chopped class fibers. These processes result in a fiber glass-coated-polyester substrate laminate. Preferably, unidirectional polymer or glass rovings (750-2,200 tex) can also be provided in the machine direction or cross-machine direction, or in both directions, to allow for the handling of the resulting laminate without significant unintended stretching. Although a uniform application of glass fibers is illustrated in the Figures, the glass fibers can be unevenly distributed on each or some of the fabric layers, or disposed in a double thickness on one fabric layer, such asfabric layer28, while not applying any fibers to the other fabric layer, such aslayer18, prior to final stitching.

Because of the glass fiber reinforcement, the cured conduit liners of this invention, for example,liners500 ofFIG. 4,300 ofFIG. 5 and 600 ofFIG. 6, will have a flexural modulus of at least about 650 ksi and, typically, about 700-800 ksi or more, with a tensile strength of at least about 4,000-9,000 psi. The glass-facedliner300 ofFIG. 5 will have a modulus of about 700-800 ksi or more, due to the outer glass-containinglayers224 and234 being located at or near the surface. These properties represent a tremendous improvement over cured 100% polyester felt conduit liners, which are known to have a flexural modulus of less than 500 ksi, and commonly about 300-400 ksi. In these forms, some embodiments of this invention use a total of no more than about 5 mm, preferably less than about 1 to about 3 mm of glass, in each of the liner blocks100,200, incomposite liners500 and300, with the balance being polyester or other fabric material. Afull thickness 100% glass liner could be used with some additional cost, such as, for example, by using a pair of needled glass felt layers with chopped glass and/or glass roving sandwiched therebetween. Alternatively, the glass component can be limited to the outermost liner blocks only, such as within liner blocks100 and400 incomposite liner600. The same would also apply to composite liners having 5, 7 and 9 liner blocks, for example.

In addition, a substantially fluid-impermeable layer20 or220, such as a membrane, coating, saturant, film or resinous latex coating, can be provided onfabric layers35 and235, and optionally on the innermost surface (prior to inversion) of the liner, such as fabric layers28 and138, or on glass-containinglayer234 ofliner300, to prevent fluid leakage and aid in pressurization. In the preferred embodiment, the fabric layers35 and235 are (1) painted or coated with a latex saturants such as polyurethane or acrylic, or (2) melt bonded to a polyethylene film, on one side only. In a preferred embodiment, a thin polyester felt of about 0.8 to about 2 mm can be heat bonded to a thermoplastic film of about 0.3 to about 0.6 mm in thickness for a final thickness of about 1.2 to about 2.3 mm.

In accordance with a preferred embodiment of this invention, shown inFIG. 7A, apreferred liner block850 has been manufactured by applying a substantially fluidimpermeable layer820 to a thin flexible fabric layer orveil828 by the methods and materials discussed above. The substantially fluidimpermeable layer820 can be applied to theveil828 and directly to the second glass-fiber containing layer824. In preparing theliner300, shown inFIG. 5, a coated polyester felt is typically supplied by an outside vendor, and is heat-bonded to thethin veil228 by aheat bond226.FIG. 7B shows a variation of this embodiment, in which theveil828 is omitted, and theimpermeable layer820 is joined directly to the secondflexible fabric layer824.FIG. 7B also shows that theflexible fabric layers818 and838 can be heat or adhesive bonded to each other without stitching or needling.

The present inventors also envision an improved construction method whereby thefabric layer235 ofFIG. 5 can be eliminated. This improved method of manufacturing a tubularinversion liner block850, includes the steps of providing a firstflexible fabric layer838 fastened to a first glassfiber containing layer834 and providing a secondflexible fabric layer818 fastened to second glassfiber containing layer824. The method then combines the first and secondflexible fabric layers838 and818 and the first and second glassfiber containing layers834 and824 so that the first and secondflexible fabric layers838 and818 face one another and are sandwiched between the first and second glassfiber containing layers834 and824. For thicker liners, additional flexible fabric layers can be added tolayers838 and818, or theselayers838 and818, and the glassfiber containing layers834 and824, can be made thicker, as set forth by way of example, in connection with the description ofliner300. A thirdflexible fabric layer828, preferably a thinner flexible fabric of the same or similar material, such as a veil, as described herein, is attached to one of theglass containing layers824 or834. In addition, a substantially fluidimpermeable layer820, much like the fluidimpermeable layers20 and220 defined herein, is joined to the third flexible fabric layer828 (as shown inFIG. 7A), or directly to one of theglass containing layers824 or834 (as shown inFIG. 7B). When the substantially fluidimpermeable layer820 is joined to the third flexible fabric layer828 (FIG. 7A) or to the second glass fiber containing layer824 (FIG. 7B) by adhesive, glue, solvent, flame, melt-bond, or stitching, for example, the substantially fluidimpermeable layer820 becomes the outermost layer, and the first or other glassfiber containing layer834 can become the innermost layer of the inversion liner orliner block850 prior to inversion. In a preferred embodiment, the substantially fluidimpermeable layer820 is applied by (1) directly coating a plastic film or painting a resinous layer, for example, onto the thin nonwoven veil orlayer828, after it and the other layers ofliner block850 have been stitched together, or (2) by separately applying a plastic film, resinous fluid or latex layer onto the thirdflexible fabric layer828 prior to stitching or joining to the remaining layers of theblock850, or (3) by layering a substantially fluidimpermeable layer820 with one of the glass fiber containing layers and flexible fabric layers before they are all stitched together.

In typical fashion, the thirdflexible fabric layer828 can be stitched to the second glassfiber containing layer824 and secondflexible fabric layer818 at the same time the latter two layers are stitched. Alternatively, the thirdflexible fabric layer828 could be stitched at the same time as the first and secondflexible fabric layers838 and818, and their attendant glassfiber containing layers834 and824, are stitched together. This practice is more desirable when a total thickness oflayers834,838,818,824 and820 is less than about 7 mm. Otherwise, it is envisioned that the first and secondflexible fabric layers838 and818 would, preferably, be heat or resin-bonded, such as disclosed by heat orresin bonds26,126 or326. After heat or resin bonding theflexible fabric layers838 and818 together, a coated felt, such asflexible fabric layer235 ofFIG. 5 and its substantially fluidimpermeable layer220, can be heat-bonded to the veil, such asveil828, in this assembly variation.

For reasons of functionality and aesthetics, a veil or thin flexible fabric layer can also be added to the surface of the firstglass containing layer834, which will eventually become the outermost layer after inversion. This will contain loose fibers from being removed from the liner, which could possibly cause irritation during handling.

For example,FIG. 8 shows anexemplary liner block950, having a firstflexible fabric layer938 and a first high strength (e.g., glass)fiber containing layer934 stitched together, and having a secondflexible fabric layer918 and a second high strength (e.g., glass)fiber containing layer924 stitched together. The first and secondflexible fabric layers938 and918, are fastened together by melt bonding or adhesion without stitching or needling, whereby the first and secondflexible fabric layers938,918 face one another and are sandwiched between the first and secondfiber containing layers934,924. A substantially fluidimpermeable layer920 is joined to at least one of the high strength fiber containing layers924. In the example shown, aveil928 is joined to the second glassfiber containing layer924 and secondflexible fabric layer918 at the same time the latter two layers are stitched. The fluidimpermeable layer920 is joined to the secondfiber containing layer924 by way of attachment to theveil layer928. Theliner block950 further comprises a anotherveil layer935 joined to the other of the first and second high strength fiber containing layers.

In this example, thesecond veil layer935 is joined to the firstflexible fabric layer938 and the first high strengthfiber containing layer934 at the same time the latter two layers are stitched. Thesecond veil935, which is initially on the inside of the liner orliner block950 protects the glass layer during production handling, and also during inversion.

The substantially fluidimpermeable layer920 may be applied to theveil layer928 or to the second glassfiber containing layer924 by any of the methods described above for joining the fluidimpermeable layers20,220 or820. For example, adhesive, glue, solvent, flame, melt-bond, may be used. When the substantially fluidimpermeable layer920 is joined, the substantially fluidimpermeable layer920 becomes the outermost layer, and thesecond veil935 can become the innermost layer of the inversion liner orliner block950 prior to inversion.

AlthoughFIG. 8 shows a single liner block or liner having one pair offlexible fabric layers938,918 and one pair of high strengthfiber containing layers934,924, any desired number of liner blocks may be joined in the manner described with reference toFIG. 6, with a fluid impermeable layer as the outermost layer (prior to inversion), and aveil935 as the innermost layer (prior to inversion).

Alternatively, for thicker liners, in some embodiments, the sequence of layers in the liner, from the innermost to outermost layers (prior to inversion) may be:
V-G-F-(N*F)-F-G-V-I,
where V=veil layer (optional), G is a high strength fiber containing layer, F is a flexible fabric layer, N is an integer greater than zero representing the number of additional flexible fabric layers, and I is a fluid impermeable layer.FIG. 9 shows an example of such a configuration. InFIG. 9, theliner1050 includes aveil layer1035, a first high strengthfiber containing layer1034, a firstflexible fabric layer1038, a desired number N of additional flexible fabric layers1019a-n, followed by aflexible fabric layer1018, a high strengthfiber containing layer1024, aveil layer1026, and a fluidimpermeable layer1020. The first high strengthfiber containing layer1034 is joined to the firstflexible fabric layer1038 by stitching, needling or the like, and the second high strengthfiber containing layer1024 is joined to the secondflexible fabric layer1018 by stitching, needling or the like. The various adjacentflexible fabric layers1038,1019a-n, and1018 are joined to each other by heat bonding or adhesive, without stitching or needling, permitting the liner to have a desired thickness that is not limited by the capabilities of stitching or needling equipment. Theveil layer1026 and the fluid impermeable layer are joined to theflexible fabric layer1024 using any of the techniques described above.

In other embodiments, for very thick designs, a layer sequence such as:
V-G-F-G-F-(N*F)-F-G-F-G-V-I,
may be used, in which each G-F-G-F block may be stitched together, and the one or more F-F bonds between these blocks would be formed with heat or adhesives.FIG. 10 shows an example of such a configuration. InFIG. 10, theliner1150 includes aveil layer1135, a first high strengthfiber containing layer1134a, a firstflexible fabric layer1138a, a second high strengthfiber containing layer1134b, a secondflexible fabric layer1138b, a desired number N of additional flexible fabric layers1119a-n, followed by a thirdflexible fabric layer1118a, a third high strengthfiber containing layer1124a, a fourth flexible fabric layer1118b, a fourth high strengthfiber containing layer1124b, aveil layer1126, and a fluidimpermeable layer1120. Each high strengthfiber containing layer1134a,1134b,1124a, and1124bis joined to a respectiveflexible fabric layer1138a,1138b,1118a, and1118bby stitching, needling or the like. The G-F-G-F blocks can be formed by stitching together two of the stitched assemblies, each containing a flexible fabric layer and its attached high strength fiber containing layer. The various adjacentflexible fabric layers1138b,1119a-n, and1118aare joined to each other by heat bonding or adhesive, without stitching or needling. Theveil layer1126 and the fluid impermeable layer are joined to the flexible fabric layer1124 using any of the techniques described above.

One of ordinary skill in the art will understand that both the configurations shown inFIG. 9 andFIG. 10 allow the high strength fibers to be concentrated furthest from the neutral axis of the liner material, to maximize the hoop and longitudinal strength provided by a relatively small volume of high strength fibers.

The membrane, film, coating or layer, such as substantiallyimpermeable layers20,220 and820, should be substantially impermeable to fluids, such as air, steam or water, at a pressure of less than 1 atmosphere (15 psi), preferably about 3-5 psi, and temperatures of about 100-260° F. For example, in one exemplary hot water cure system of this invention, the temperature of the water can be cycled up to 180-190° F. More specifically, the heat can be applied from one side, ramped from ambient to 180° F. over 3-4 hours, and held at 140° F. for one-half hour. The exothermic reaction for a thermosetting resin can occur, for example, during the 140° F. hold, and peak at 250-260° F. A temperature of 180° F. is maintained for 3 hours, then the liner is cooled at a rate of no higher than about 15° F. per hour down to about 10° F. over ambient. The substantiallyimpermeable layers20,220 and820 can be attached to a thin flexible fabric layer, such as aveil228, or attached directly to a thicker flexible fabric layer, such aslayers235 or18, or directly attached to a glass fiber containing layer, such aslayers224,24 or824 (as inFIG. 7B), via adhesive, glue, solvent, flame, melt-bond or stitching for example.

Theliners300,500 and600, and blocks100,200,400 and850 of the present examples of this invention are designed to be impregnated with a curable or settable resin. The resinous impregnation liquid introduced into the fabric layers18,28,35,138,148,218,238,228,235,838,818,318, and/or328, glass fiber-containinglayers24,34,134,124,834,824 and/or224, or within all or some of these layers, can be any number of thermosetting or thermoplastic compositions which can be introduced by dipping, injecting, extruding or painting, for example. The resinous impregnation liquid becomes set or hardened by light or heat to provide a solid matrix around the fibers. Suitable thermoplastic compositions include thermoplastic polyvinyl chloride, polyolefins, and the like. Suitable thermosetting resins can include those containing a heat-activatable curing agent, a light-activatable agent, a curing agent, or a heat deactivatable curing retarding agent. Such examples include ultraviolet curing unsaturated polyester, such as disclosed in U.S. Pat. No. 6,170,531, incorporated herein by reference, vinyl ester, epoxy and thermosetting polyester.

Theliners300,500 and600, and optionally, liner blocks100,200,850 and400 of the disclosed examples of this invention further include an adhesive, glue, solvent, flame and/or meltbonds26,126,226 and326. Thebonds26,126,226 and326 preferably include a flame or melt bond between molten fibers of polyester felt or polyolefin fibers, for example. Thebonds26,126,226 and326 preferably “tack” the adjoining layers together so that they can be resin impregnated, inserted into a pipe and inverted under pressure without breaking apart. Curing of the resinous saturant will provide the final bond between fabric and glass layers to provide the final tensile and flexural strength.

With respect toFIG. 1, one procedure for inserting thepreferred inversion liner500 of this invention will now be described. This improved method is designed to repair a crack in a rupturedunderground conduit12, such as pipes, mains or drains. Man holes, when not already present, can be provided on opposite sides of the ruptured pipe sections after thepipe12 has been suitably emptied and the particular section is uncoupled from adjacent sections. Theunexpanded inversion liner500, containing thecomposite liner portions100 and200 ofFIG. 4, is then inserted into the cleanedpipe12, thefree end11 is then inverted and clamped byfasteners13 to thefeed elbow22. Hot pressured fluids, such as steam, air or water can be pumped into theliner500 until it completely inverts and expands. This pressure can remain within theliner500 until the thermosetting or thermoplastic resin impregnated therein sets or cures. The free end of theliner500 can then be removed from theelbow22 and the repaired section of thepipe12 re-coupled to the adjacent pipe sections. The liners and liner blocks100,200,300,500,600 and850 according to the exemplary embodiments of this invention may also be used with new or undamaged conduit before installation, or can be used to manufacture original equipment piping and conduit, as a liner, or as a stand alone product.

From the foregoing, it can be realized that this invention provides improved inversion liners having reinforced glass (or other high strength) fiber-containing layers for improving the hoop and longitudinal strength of the liner material, while providing a heat or light-activatable saturant for curing. Although various embodiments have been illustrated, this is for the purpose of describing, but not limiting the invention. Various modifications, which will become apparent to one skilled in the art, are within the scope of this invention described in the attached claims and equivalents thereof.

Claims (36)

What is claimed:

1. A method of making a tubular inversion liner or liner block, comprising:

a) providing a first flexible fabric layer stitched to a first high strength fiber containing layer;

b) providing a second flexible fabric layer stitched to a second high strength fiber containing layer;

c) combining said first and second flexible fabric layers and said first and second high strength fiber containing layers by melt bonding or adhesion without stitching or needling the first and second flexible fabric layers to each other, whereby said first and second flexible fabric layers face one another, and are sandwiched between said first and second high strength fiber containing layers; and

d) providing a substantially fluid impermeable layer on said second high strength fiber containing layer to form a tubular inversion liner having a total thickness of about 12 to 50 mm.

2. The method ofclaim 1 wherein said first and second flexible fabric layers comprise a nonwoven polyester felt.

3. The method ofclaim 1 wherein said first and second high strength fiber layers comprise at least one of the group consisting of chopped glass fibers and glass roving.

4. The tubular inversion liner ofclaim 1 wherein said substantially fluid impermeable layer comprises one of a resinous membrane or a resinous coating.

5. The tubular inversion liner ofclaim 4 wherein said substantially fluid impermeable layer further comprises a veil to which the resinous membrane or resin coating is applied.

6. The method ofclaim 4 wherein said fluid impermeable layer comprises a polyurethane coating which is adhered to a first surface portion of one or both of said high strength fiber containing layers.

7. The method ofclaim 6, wherein said fluid impermeable layer has a thickness of about 0.3 to about 0.6 mm.

8. The method ofclaim 1 wherein said liner is impregnated with a heat curable or light curable resin, and cured to produce a flexural modulus of at least about 650 ksi.

9. The method ofclaim 1 comprising an additional flexible fabric layer, high strength fiber containing layer, or both, disposed between said first and second flexible fabric layers.

10. The method ofclaim 1 wherein said liner is an inversion liner and said substantially fluid impermeable layer becomes the outermost layer prior to inversion, and the innermost layer following inversion.

11. The method ofclaim 1, further comprising one or more further flexible fabric layers between the first and second flexible fabric layers, the further flexible fabric layers having a thickness of about 10 mm to about 20 mm.

12. A method of making a tubular inversion liner or liner block, comprising:

a) providing a first flexible fabric layer stitched to a first high strength fiber containing layer;

b) providing a second flexible fabric layer stitched to a second high strength fiber containing layer, the second high strength fiber containing layer including chopped fibers and rovings;

c) combining said first and second flexible fabric layers and said first and second high strength fiber containing layers by melt bonding or adhesion without stitching or needling the first and second flexible fabric layers to each other, whereby said first and second flexible fabric layers face one another, and are sandwiched between said first and second high strength fiber containing layers;

d) joining a veil to the second high strength fiber containing layer, the veil being thinner than the first and second flexible fabric layers;

e) providing a substantially fluid impermeable layer on said veil, wherein said fluid impermeable layer comprises a polymer film directly bonded to the veil.

13. The method ofclaim 12 further comprising joining a second veil to the first high strength fiber containing layer.

14. The method ofclaim 12, wherein the liner has a total thickness of about 12 mm to about 50 mm.

15. The method ofclaim 12, wherein the liner block has a thickness of about 9 mm.

16. A pressure-expandable tubular liner for conduits, including at least one liner block, comprising:

a first flexible fabric layer stitched to a first high strength fiber containing layer;

a second flexible fabric layer stitched to a second high strength fiber containing layer;

said first and second flexible fabric layers and said first and second high strength fiber containing layers fastened together by melt bonding or adhesion without stitching or needling the first and second flexible fabric layers to each other, whereby said first and second flexible fabric layers face one another and are sandwiched between said first and second fiber containing layers; and

a substantially fluid impermeable layer joined to at least one of said high strength fiber containing layers to form a tubular inversion liner having a total thickness of about 12 to 50 mm.

17. The tubular inversion liner ofclaim 16, wherein said first and second flexible fabric layers comprise a nonwoven polyester felt.

18. The tubular inversion liner ofclaim 17, wherein said first and second high strength fiber layers comprise at least one of the group consisting of chopped glass fibers and glass roving.

19. The tubular inversion liner ofclaim 16, wherein said substantially fluid impermeable layer comprises one of a resinous membrane or a resinous coating.

20. The tubular inversion liner ofclaim 19 wherein said substantially fluid impermeable layer further comprises a veil to which the resinous membrane or resin coating is applied.

21. The tubular inversion liner ofclaim 16, wherein said fluid impermeable layer comprises a polyurethane coating which is adhered to a first surface portion of one or both of said high strength fiber containing layers.

22. The tubular inversion liner ofclaim 16, wherein said fluid impermeable layer comprises a polymer film integrally bonded to a felt, veil or both.

23. The method ofclaim 22, wherein said veil has a thickness of from about 0.1 mm about 1.0 mm.

24. The method ofclaim 22, wherein said veil has a thickness of from about 0.1 to about 1.0 mm.

25. The method ofclaim 16, wherein said substantially fluid impermeable layer comprises a polyurethane or acrylic latex coating, or a melt-bonded polyolefin film.

26. The tubular inversion liner ofclaim 16 wherein said liner is impregnated with a heat curable or light curable resin, and cured to produce a flexural modulus of at least about 650 ksi.

27. The tubular inversion liner ofclaim 16 comprising an additional flexible fabric layer, high strength fiber containing layer, or both, disposed between said first and second flexible fabric layers.

28. The tubular liner ofclaim 16 wherein said liner is an inversion liner and said substantially fluid impermeable layer becomes the outermost layer prior to inversion, and the innermost layer following inversion.

29. The liner ofclaim 16, wherein the liner block has a thickness of about 9 mm.

30. The liner ofclaim 16, further comprising a further flexible fabric layer between the first and second flexible fabric layers, the further flexible fabric layer having a thickness of from about 10 mm to about 20 mm.

31. The tubular inversion liner ofclaim 16, further comprising a veil layer joined to the other of said high strength fiber containing layers.

32. A pressure-expandable tubular liner for conduits, comprising:

a first flexible fabric layer stitched to a first high strength fiber containing layer;

a second flexible fabric layer stitched to a second high strength fiber containing layer;

one or more additional flexible fabric layers, each of the additional flexible fabric layers joined to one of the group consisting of the first flexible fabric layer, the second flexible fabric layer, and another of the one or more additional flexible fabric layers by melt bonding or adhesion without stitching or needling the first and second flexible fabric layers to each other, whereby said one or more additional flexible fabric layers are sandwiched between said first and second high strength fiber containing layers; and

a substantially fluid impermeable layer joined to at least one of said first and second high strength fiber containing layers to form a tubular inversion liner having a total thickness of about 12 to 50 mm.

33. The liner ofclaim 32, further comprising a thin felt or veil layer sandwiched between the second high strength fiber containing layer and the substantially fluid impermeable layer.

34. The liner ofclaim 32, further comprising a thin felt or veil layer joined to the first high strength fiber containing layer.

35. The liner ofclaim 32, further comprising:

a third flexible fabric layer fastened to a third high strength fiber containing layer and joined between the first flexible fabric layer and the additional flexible fabric layers; and

a fourth flexible fabric layer fastened to a fourth high strength fiber containing layer and joined between the second flexible fabric layer and the additional flexible fabric layers.

36. The liner ofclaim 32, further comprising:

a first thin felt or veil layer sandwiched between the second fiber containing layer and the substantially fluid impermeable layer;

a second thin felt or veil layer joined to the first fiber containing layer;

a third flexible fabric layer fastened to a third high strength fiber containing layer and joined between the first flexible fabric layer and the additional flexible fabric layers; and

a fourth flexible fabric layer fastened to a fourth high strength fiber containing layer and joined between the second flexible fabric layer and the additional flexible fabric layers,

wherein the one or more additional flexible fabric layer includes a plurality of adjacent additional flexible fabric layers joined to each other by melt bonding or adhesion without stitching or needling the adjacent additional flexible fabric layers to each other.

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